Eddy or whirling mill



- v E. KRAMER ETAL EDDY OR WHIRLING MILL Filed July 13, 1927 Patented -May 29, 192 8. J

UNITED STAT-ES I 1,671,678" PATENT OFFICE.

' ERWIN KRAMER, OF BERLIN, AND EMIL PODSiUS, F BEBLIN-FBIEDRICKSHAGEN,

-GEBMANY, A SSIGNOBS TO HARTSTOFF-ME TALL AKTIENGESELLSCHAFT (HAMB- TAG), OF BEBLIN COPENICK, GERMAI NY.

EDDY OR WHIRLING MILL.

Application filed July 13, 1927, Serial No. 205,298, and in Germany November 7, 1925.

This. invention relates in general to eddy or whirling mills.

An'object of the invention is to im rove the known whirling mills, see U. P. 1,573,017, in which the small pulverizing particles are caused to repeatedly impinge upon one another by two or more mutually impinging whirling currents that are pre- 'vented from evading each other. In'these mills the casing, when properly shaped, is filled with whirling currents, but the strength of these currents is not the same throughout so that there may be zones in the casing where the currents are weaker and where powder of relatively great specific weight etc. is deposited and thus prevented from completely participating in the pulverizing process in the mill. Such an action is particularly undesirable in cases in which a definite quantity of material Is to be operated upon uniformly throughout. One object of the invention is to eliminate this imperfect action. Other advantages are also obtained.

Assumin that the power applied'to the shafts of t e machine or mill is constant, the invention renders it possible to vary between very appreciable limits the quantity of material fed into the mill at which its driving power is fully utilized. Consequently it is possible to reduce the quantity of material undergoing pulverization in the mill to a very small amount and cut down the time that the material remains therein. This is particularly valuable in, cases in which materials are to be pulverized which, in their ordinary state or a whirled up condition, are explosive, or tend to form chemical combinations with other solid or gaseous.

stuffs contained in the mill. On the other hand the time that the material remains in the mill .can be arranged to be just sufiicient to accomplish the desired combinations or effects. These effects maybe of a mechanical'naturewhereby a more or less jagged form or a more rounded shape is imparted to the particles. This possibility of variation is particularly valuable when metals are to be pulverized. Another feature of the invention is that it enables the material in the mill casing to be forced to participate to a greater extent thanhitherto in the roeess of pulverization. By this means t e efficiency of the mill 1s increased and the harmterial that is stirred up mechanically is then I seized the more effectively by the whirling currents and subjected to the intended pulverization process. The mechanical stirrin members may be made to act on the materia so as to assist in the process of pulverization itself in addition to roducing the stirring effect. The practica means employed! to obtain the aforesaid results are preferably in the form of rotating arms mounted on the shafts of the propellers and extending therefrom to within a slight distance of the in- .terior wall of the mill casing-;' but of course not close enough to scrape against said wall. The closer the stirring members sweep along the wall of the casing, the smaller will be the quantity of material that is notseized and stirred up by said members. The effectiveness of the stirring arms can be increased by increasing their breadth adjacent or parallel to the wall of the casing, which may be accomplished by making them hookshaped, T-shaped, etc. The stirring members may also be obtained by shaping the known transverse members used for turning the whirling currents so that they also act as mechanical stirring members.

The invention is shown by way of example in the drawing in which Fig. 1 is a longitudinal section through a null equipped with two propellers and stirring members, and s Fig. 2 is a partial longitudinal section showinga modified form and arrangement of stirring member.

J ournalled in the casing 1 are two shafts 2 and 3 which carry the propellers 4 and 11 that produce whirling air currents. Also mounted'on the shafts 2 and 3am stirring members or arms 5 and 6 which extend from the shaft to within a short distance from the inner surface of the wall of the casing 1 where they are formed in the shape of IOI hooks 7 8. The arms 5, 6 as shown also act as transverse members of the known t pe and are fixed on internally of the propel ers 4 and 11. In a practical machine they are displaced radially with respect to the propellers 4 and 5 at an angle of say 90 although they are shown for clearness in the drawing as if they were in line with, or in the same plane as, the propellers.

A partial longitudinal section of a moditied construction of mill is shown in Fi 2. The ends of the arm 5 extend to the rlght and left of its radial limb so as to form two hooks 9 and 10 or a kind of T. The arm 5 is arranged externally of the propcllcr 4. Also with this arrangement it is preferred to displace the arm radially with respect to the propeller by about 90.

The constructional form shown in Fig. 2 is preferred in cases in which the material to be ground tends to adhere to the wall of the casing.

As stated above the mills shown in the drawing are only examples ofthe invention. According to the requirements of each particular case the one or another form of device or combinations of different suitable forms willbe employed. For instance the arms 5 and 6 may be equipped on one side with inwardly extending hooks and on the other side with outwardly extending hooks etc. Or the propellers themselves may be provided with elongations that act as stir ring members. Furthermore a separate shaft may be placed in the bottom part of as the casing with stirring members that stir up the material from the bottom of the casing where deposits of the same are particularly liable to occur.

We claim v 1. In a device for pulverizing hard materials, in combination with an entirely enclosed casing containing gas or air and material to be pulverized, means for producing therein whirling currents of mutually impinging particles and for circulating said particles within said casing with great velocity, and additional mechanical moving members for moving material from outside the impinging zone into the whirling currents.

2. In the combination of claim 1, said additional mechanical members comprisin rotary shafts and arms extending from sai shafts substantially to the walls of said casing.

In testimony whereof we have afixed our signatures.

ERWIN KRAMER. EMIL PODSZUS. 

